go pflag命令行参数解析详解

文章目录

• ​​1. pflag简介​​
• ​​2. 安装​​
• ​​3. 用法​​

• ​​3.1 练习1​​
• ​​3.2 练习2​​
• ​​练习三 flag.Lookup​​

• ​​4. flag与pflag混用​​

1. pflag简介

pflag是Go的flag包的直接替代，实现了POSIX / GNU样式的–flags。pflag是Go的本机标志包的直接替代。如果您在名称“ flag”下导入pflag，则所有代码应继续运行且无需更改。

github：​​https://github.com/spf13/pflag​​​ 源码包：​​https://godoc.org/github.com/spf13/pflag#Args​​

默认标志位：​​--​​

--flag    // boolean flags, or flags with no option default values
--flag x  // only on flags without a default value
--flag=x

2. 安装

$ go get github.com/spf13/pflag

3. 用法

3.1 练习1

package main

import (
    flag "github.com/spf13/pflag"  //替换原生的flag，并兼容
    "fmt"
)

var flagvar1 int
var flagvar2 bool

func init() {
    flag.IntVar(&flagvar1, "varname1", 1, "help message for flagname")
   flag.BoolVarP(&flagvar2, "boolname1", "b", true, "help message")
}


func main() {
   var ip1 *int = flag.Int("flagname1", 1, "help message for flagname")
   
   var ip2 = flag.IntP("flagname2", "f", 2, "help message") 
   
   

   flag.Parse()
   
   fmt.Println("ip1 has value ", *ip1)
   fmt.Println("ip2 has value ", *ip2)
   fmt.Println("flagvar1 has value ", flagvar1) 
   fmt.Println("flagvar2 has value ", flagvar2) 
}

$ go build fplag1.go
/pflag1 -h
Usage of ./pflag1:
  -b, --boolname1       help message (default true)
      --flagname1 int   help message for flagname (default 1)
  -f, --flagname2 int   help message (default 2)
      --varname1 int    help message for flagname (default 1)
pflag: help requested

3.2 练习2

package main

import (
   "github.com/spf13/pflag"
   "net"
   "fmt"
   "time"
)

func pflagDefine() {
   //64位整数，不带单标志位的
   var pflagint64 *int64 = pflag.Int64("number1", 1234, "this is int 64, without single flag")

   //64位整数，带单标志位的
   var pflagint64p *int64 = pflag.Int64P("number2", "n", 2345, "this is int 64, without single flag")

    //这种可以把变量的定义和变量取值分开，适合于struct，全局变量等地方
   var pflagint64var int64
   pflag.Int64Var(&pflagint64var, "number3", 1234, "this is int64var")

   //上面那一种的增加短标志位版
   var pflagint64varp int64
   pflag.Int64VarP(&pflagint64varp,"number4", "m", 1234, "this is int64varp")



    //slice版本,其实是上面的增强版，但是支持多个参数，也就是导成一个slice
    var pflagint64slice *[]int64 = pflag.Int64Slice("number5", []int64{1234, 3456}, "this is int64 slice")

    //bool版本
    var pflagbool *bool = pflag.Bool("bool", true, "this is bool")

    //bytes版本
    var pflagbyte *[]byte = pflag.BytesBase64("byte64", []byte("ea"), "this is byte base64")

    //count版本
    var pflagcount *int= pflag.Count("count", "this is count")

    //duration版本
    var pflagduration *time.Duration = pflag.Duration("duration", 10* time.Second, "this is duration")

    //float版本
    var pflagfloat *float64 = pflag.Float64("float64", 123.345, "this is florat64")

    //IP版本
   var pflagip *net.IP = pflag.IP("ip1", net.IPv4(192, 168, 1, 1), "this is ip, without single flag")

   //mask版本
    var pflagmask *net.IPMask= pflag.IPMask("mask", net.IPv4Mask(255,255,255,128),"this is net mask")

   //string版本
    var pflagstring *string= pflag.String("string", "teststring", "this is string")

   //uint版本
   var pflaguint *uint64 = pflag.Uint64("uint64", 12345, "this is uint64")

   pflag.Parse()
   fmt.Println("number1 int64 is ", *pflagint64)
   fmt.Println("number2 int64 is ", *pflagint64p)
   fmt.Println("number3 int64var is ", pflagint64var)
   fmt.Println("number4 int64varp is", pflagint64varp)
   fmt.Println("number5 int64slice is", *pflagint64slice)
    fmt.Println("bool is ", *pflagbool)
    fmt.Println("byte64 is ", *pflagbyte)
    fmt.Println("count is ", *pflagcount)
    fmt.Println("duration is ", *pflagduration)
    fmt.Println("float is ", *pflagfloat)
   fmt.Println("ip1 net.ip is ", *pflagip)
    fmt.Println("mask is %s", *pflagmask)
    fmt.Println("string is ", *pflagstring)
   fmt.Println("uint64 is ", *pflaguint)

}

func main() {
   pflagDefine()

}

$ go build pflag2.go
$ ./pflag2 -h
Usage of ./pflag1:
      --bool                 this is bool (default true)
      --byte64 bytesBase64   this is byte base64 (default ZWE=)
      --count count          this is count
      --duration duration    this is duration (default 10s)
      --float64 float        this is florat64 (default 123.345)
      --ip1 ip               this is ip, without single flag (default 
      --mask ipMask          this is net mask (default ffffff80)
      --number1 int          this is int 64, without single flag (defa
  -n, --number2 int          this is int 64, without single flag (defa
      --number3 int          this is int64var (default 1234)
  -m, --number4 int          this is int64varp (default 1234)
      --number5 int64Slice   this is int64 slice (default [1234,3456])
      --string string        this is string (default "teststring")
      --uint64 uint          this is uint64 (default 12345)
pflag: help requested

练习三 flag.Lookup

flag包中提供了一种类似上述的”配置中心”的机制，但这种机制不需要我们显示注入“flag vars”了，我们只需按照flag提供的方法在其他package中读取对应flag变量的值即可。

$tree flaglookup
flaglookup
├── etcd
│   └── etcd.go
└── main.go

// flag-demo/flaglookup/main.go
package main

import (
    "flag"
    "fmt"
    "time"

    "./etcd"
)

var (
    endpoints string
    user      string
    password  string
)

func init() {
    flag.StringVar(&endpoints, "endpoints", "127.0.0.1:2379", "comma-separated list of etcdv3 endpoints")
    flag.StringVar(&user, "user", "", "etcdv3 client user")
    flag.StringVar(&password, "password", "", "etcdv3 client password")
}

func usage() {
     fmt.Println("flagdemo-app is a daemon application which provides xxx service.\n")
     fmt.Println("Usage of flagdemo-app:\n")
     fmt.Println("\t flagdemo-app [options]\n")
    fmt.Println("The options are:\n")

    flag.PrintDefaults()
}


func main() {
    flag.Usage = usage
    flag.Parse()

    go etcd.EtcdProxy()

    time.Sleep(5 * time.Second)
}

// flag-demo/flaglookup/etcd/etcd.go
package etcd

import (
    "flag"
    "fmt"
)

func EtcdProxy() {
    endpoints := flag.Lookup("endpoints").Value.(flag.Getter).Get().(string)
    user := flag.Lookup("user").Value.(flag.Getter).Get().(string)
    password := flag.Lookup("password").Value.(flag.Getter).Get().(string)

    fmt.Println(endpoints, user, password)
}

[root@localhost flaglookup]# go run main.go -endpoints 192.168.10.69:2379,10.10.12.36:2378 -user tonybai -password xyz123
192.168.10.69:2379,10.10.12.36:2378 tonybai xyz123

4. flag与pflag混用

混用flag及pflag时，注意使用的方法

import (
  goflag "flag"
  flag "github.com/spf13/pflag"
)

var ip *int = flag.Int("flagname", 1234, "help message for flagname")

func main() {
  flag.CommandLine.AddGoFlagSet(goflag.CommandLine)
  flag.Parse()
}